If confirmed by the Senate as a justice, Kagan would have to sit out high court review of the government's decade-old racketeering lawsuit against cigarette makers. That's because she already has taken sides as solicitor general, signing the Obama administration's Supreme Court brief in the case — an automatic disqualifier.
Kagan is expected to step aside from 11 of the 24 cases the court has so far agreed to hear beginning in October.
Without her, the government and anti-tobacco advocates could find it difficult, if not impossible, to find a fifth vote to allow the government to seek $280 billion of past tobacco profits and $14 billion for a national campaign to curb smoking.
The justices are expected to consider whether to take up the tobacco lawsuit at their private conference on June 24. If they decide to go ahead, they would hear argument in the fall or winter.
A justice's decision not to participate in a case, called a recusal, can have a dramatic effect on a nine-person court. The court has split 4-4 on several occasions in recent years when justices did not take part in a case because they owned stock in an affected company, had a relative involved in some way or had participated in the case either as a lawyer or judge.